One more thing to think about is that when the 2010 does come out, since it will be a new model and the fact that the economy is still slumping and that trend may still be happening when the 2010 comes out, you can check out the 2010, decide if you like it, and if not, I bet they will firesale the 09's to get them off the lot since they would be obsolete next to the new model.
That way, you get the opportunity to at least consider the new model, but if you choose the 4th gen you could probably get almost the same deal you're looking at now.
Its obviously your call, but I just don't understand spending almost 30 large on ALMOST the same vehicle you have now.